One of the new words I picked up while reading Survival of the Sickest was transposon. Wikipedia describes transposons as:

sequences of DNA that can move around to different positions within the genome of a single cell, a process called transposition. In the process, they can cause mutations and change the amount of DNA in the genome.
….
While transposons may confer some benefits on their hosts, they are generally considered to be selfish DNA parasites that live within the genome of cellular organisms.

Also known as “jumping genes,” these transposons add a new element to the study of epigenetics. Now here’s where it gets really fun. Just as mitochondria are thought to have evolved from early organisms that developed a symbiotic relationship with eukaryotes, supplying aerobic powers in exchange for a constant food supply, one class of transposons, known as retrotransposons, function much like retroviruses like HIV, a clue to their evolutionary origin. Rather than the DNA being imprinted on the RNA through the use of transcriptase, retroviruses use reverse transcriptase to imprint their RNA onto host DNA, replicating when the host DNA replicates. It’s quite likely that you and every other human is carrying around quite a load of viral DNA in your own. Isn’t evolution fun?

There’s also a second class of transposons that work by moving themselves around in a “cut and paste” type of operation. These are the type of transposons that I recall being discussed in the book regarding extremely fast “evolution” in maize by these genes moving around in the genome to compensate for environmental factors. It’s really all quite fascinating to think that DNA is a living organism. Of course, these transposons can also be a bad thing if they are able to insert viral DNA into our own.

Diseases that are often caused by transposons include hemophilia A and B, severe combined immunodeficiency, porphyria, predisposition to cancer, and Duchenne muscular dystrophy.

Anyway, nothing especially useful here, I just find it very interesting to understand the biology of the body.


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